Energy is ever-existing - energy does not disappear or is not created from nothing. Energy is only transferred from one system to another. Energy is only transformed from one type/form of energy to another type/form of energy. So, the energy of a system is either converted into another type of energy in that same system or is extinct to another system.
If organisms can not adapt they become extinct.
The correct answer is C.) Getting food. Unlike plants, which have the ability to produce enough food through photosynthesis, heterotrophs, which include all animals (Invertebrates are animals as well) must gain their food from outside sources. Hope this helped!